for review: maybe_int option

[Andrew Bromage]

Fergus, could you please review this (very small) change?  Thanks.


Estimated hours taken: 1.0

library/getopt.m:
	Added a new kind of option: maybe_int.  Also added
	getopt__lookup_maybe_int_option/3 to look up options of
	type maybe_int.

NEWS:
	Note the new option type.


Index: NEWS
===================================================================
RCS file: /home/staff/zs/imp/mercury/NEWS,v
retrieving revision 1.90
diff -u -r1.90 NEWS
--- NEWS	1997/12/09 04:09:27	1.90
+++ NEWS	1997/12/19 02:27:49
@@ -227,6 +227,11 @@
   `MGNUCFLAGS=-DML_OMIT_ARRAY_BOUNDS_CHECKS' in your Mmake file). 
   [XXX we also need to fix problems with intermodule inlining heuristics.]
 
+* We've added a new type of option data: maybe_int(maybe(int)).
+  There is also a new corresponding lookup predicate,
+  getopt__lookup_maybe_string_option/3.  See library/getopt.m for
+  details.
+
 * The support for debugging using Prolog now includes support for
   detailed control over how terms are printed out during debugging.
 
Index: library/getopt.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/library/getopt.m,v
retrieving revision 1.17
diff -u -r1.17 getopt.m
--- getopt.m	1997/11/29 14:47:33	1.17
+++ getopt.m	1997/12/04 05:09:23
@@ -114,6 +114,7 @@
 	--->	bool(bool)
 	;	int(int)
 	;	string(string)
+	;	maybe_int(maybe(int))
 	;	maybe_string(maybe(string))
 	;	accumulating(list(string))
 	;	special
@@ -147,6 +148,10 @@
 :- pred getopt__lookup_string_option(option_table(Option), Option, string).
 :- mode getopt__lookup_string_option(in, in, out) is det.
 
+:- pred getopt__lookup_maybe_int_option(option_table(Option), Option,
+		maybe(int)).
+:- mode getopt__lookup_maybe_int_option(in, in, out) is det.
+
 :- pred getopt__lookup_maybe_string_option(option_table(Option), Option,
 		maybe(string)).
 :- mode getopt__lookup_maybe_string_option(in, in, out) is det.
@@ -417,6 +422,19 @@
 	;
 		error("string argument expected in getopt__process_option")
 	).
+getopt__process_option(maybe_int(_), Option, Flag, MaybeArg, _OptionOps,
+		OptionTable0, Result) :-
+	( MaybeArg = yes(Arg) ->
+		( string__to_int(Arg, IntArg) ->
+			map__set(OptionTable0, Flag, maybe_int(yes(IntArg)),
+					OptionTable),
+			Result = ok(OptionTable)
+		;
+			getopt__numeric_argument(Option, Arg, Result)
+		)
+	;
+		error("integer argument expected in getopt__process_option")
+	).
 getopt__process_option(maybe_string(_), _Option, Flag, MaybeArg, _OptionOps,
 		OptionTable0, Result) :-
 	( MaybeArg = yes(Arg) ->
@@ -482,6 +500,10 @@
 		( OptionData = bool(_) ->
 			map__set(OptionTable0, Flag, bool(no), OptionTable),
 			Result = ok(OptionTable)
+		; OptionData = maybe_int(_) ->
+			map__set(OptionTable0, Flag, maybe_int(no),
+					OptionTable),
+			Result = ok(OptionTable)
 		; OptionData = maybe_string(_) ->
 			map__set(OptionTable0, Flag, maybe_string(no),
 					OptionTable),
@@ -532,6 +554,7 @@
 getopt__need_arg(bool(_), no).
 getopt__need_arg(int(_), yes).
 getopt__need_arg(string(_), yes).
+getopt__need_arg(maybe_int(_), yes).
 getopt__need_arg(maybe_string(_), yes).
 getopt__need_arg(accumulating(_), yes).
 getopt__need_arg(special, no).
@@ -596,6 +619,13 @@
 		Val = Val0
 	;
 		error("Expected string option and didn't get one.")
+	).
+
+getopt__lookup_maybe_int_option(OptionTable, Opt, Val) :-
+	( map__lookup(OptionTable, Opt, maybe_int(Val0)) ->
+		Val = Val0
+	;
+		error("Expected maybe_int option and didn't get one.")
 	).
 
 getopt__lookup_maybe_string_option(OptionTable, Opt, Val) :-